Yes, that's a meltdown all right. Ah, probably more of a "shutdown". I get them too. If pushed to talk or told to get over it, I then go into full meltdown mode. Thankfully, it doesn't happen much now and rarely did at school. I internalised upset and rage for many years and then it began blowing out when I had to leave home permanently. There is still a lot there just under the surface.
It is a very distressing situation - the poor kid! He's probably upset because the kids leave him out, plus he might have been told off by the teacher during the day.
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Break out you Western girls,
Someday soon you're gonna rule the world.
Break out you Western girls,
Hold your heads up high.
"Western Girls" - Dragon